Method is executed twice, but it shows one

Hi!

So I have this really strange problem… Or hidden feature. I created a plugin for event registration. I has a list of events, a form to register for an event, and Brevo implementation for sending emails. Everything works just perfect on my local environment.

However… When I use the plugin on my own website, the (sql) query for inserting the registration is executed twice. The sending of a confirmation e-mail, which is in the same function, is also send twice. The registration gets a GUID for activation and that GUID is not the same for both registrations.

When I do a simple echo in the function where the registration is inserted in the database and sends the e-mail, I only see one echo printed in my page. For me, this is magic.

This is a part of the function and class that handles the registration:

if (!class_exists('Shortcodes_EventRegistration')) {
? ? class Shortcodes_EventRegistration
? ? {
? ? ? ? private $event;
? ? ? ? private $stored = false;

? ? ? ? function __construct($frmid)
? ? ? ? {
? ? ? ? ? ? if(!isset($_GET["eid"])){
? ? ? ? ? ? ? ? echo "Event key not found.";
? ? ? ? ? ? ? ? return;
? ? ? ? ? ? }

? ? ? ? ? ? global $wpdb;

? ? ? ? ? ? $query = "select eventdate.*, events.name, tz.name as timezone from {$wpdb->prefix}klc_events_dates as eventdate
? ? ? ? ? ? ? ? ? ? ? ? inner join {$wpdb->prefix}klc_events as events on eventdate.eventId = events.id
? ? ? ? ? ? ? ? ? ? ? ? inner join {$wpdb->prefix}klc_events_timezones as tz on tz.id = eventdate.timezoneId
? ? ? ? ? ? ? ? ? ? ? ? where eventdate.id = {$_GET["eid"]};";

? ? ? ? ? ? $this->event = $wpdb->get_row($query);

? ? ? ? ? ? if (isset($_POST["formaction"]) && $_POST["formaction"] = "send_eventregistration") {
? ? ? ? ? ? ? ? echo "<div>Storing and sending<div>"; // This is shown once, but executed twice
? ? ? ? ? ? ? ? $fullName = $_POST["reg"];
? ? ? ? ? ? ? ? $activationKey = $this->GUID();

                // I disabled this, because it keeps sending emails (twice)
? ? ? ? ? ? ? ? // $emailClass = new My_Email();
? ? ? ? ? ? ? ? // $emailClass->sendEventRegistationConfirmation($this->event, $fullName["fields"][1], $fullName["fields"][0], $activationKey);

? ? ? ? ? ? ? ? $query2 = $wpdb->prepare(
? ? ? ? ? ? ? ? ? ? "INSERT INTO {$wpdb->prefix}klc_events_registrations (eventdateid, fullname, country, email, experience, activationkey, activated)
? ? ? ? ? ? ? ? values (%d, %s, %s, %s, %d, %s, %s)",
? ? ? ? ? ? ? ? ? ? $_POST["eventdateid"],
? ? ? ? ? ? ? ? ? ? $fullName["fields"][0],
? ? ? ? ? ? ? ? ? ? $fullName["fields"][6],
? ? ? ? ? ? ? ? ? ? $fullName["fields"][1],
? ? ? ? ? ? ? ? ? ? $fullName["fields"][2],
? ? ? ? ? ? ? ? ? ? $activationKey, // Activation key is a GUID and always unique. Also for both registrations
? ? ? ? ? ? ? ? ? ? 0
? ? ? ? ? ? ? ? );

? ? ? ? ? ? ? ? $wpdb->query($query2);
? ? ? ? ? ? ? ? echo "<div>" . $query2 . "</div>"; // Query is shown once, but executed twice
? ? ? ? ? ? ? ? $this->stored = true;

? ? ? ? ? ? }

? ? ? ? ? ? if (!$this->stored) {
? ? ? ? ? ? ? ? $this->generateHTML();
? ? ? ? ? ? } else {
? ? ? ? ? ? ? ? $this->registrationSend();
? ? ? ? ? ? }

? ? ? ? }

? ? ? ? function GUID()
? ? ? ? {
? ? ? ? ? ? if (function_exists('com_create_guid') === true) {
? ? ? ? ? ? ? ? return trim(com_create_guid(), '{}');
? ? ? ? ? ? }

? ? ? ? ? ? return sprintf('%04X%04X-%04X-%04X-%04X-%04X%04X%04X', mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(16384, 20479), mt_rand(32768, 49151), mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535));
? ? ? ? }

// Other code is HTML to show the form or a message that the registration is stored.

And this is part of the HTML form:

<form method="POST">
    <input type="hidden" value="send_eventregistration" name="formaction" />
    <input type="hidden" value="<?= $_GET[" eid"] ?>" name="eventdateid" />
    <div id="wpforms-16958-field_0-container" class="wpforms-field wpforms-field-name" data-field-id="0">

        <input type="text" id="reg-field_0" name="reg[fields][0]" placeholder="Enter your full name" required="">
        <input type="email" id="reg-field_1" name="reg[fields][1]" placeholder="Enter your email address"
            required="">

        <div>
            <select id="reg-field_6" name="reg[fields][6]" aria-invalid="false" placeholder="Your country">
                
            </select>
        </div>
        <div class="experience">
            <p>
                Which of the following description would describe your experience with C#?
            </p>
            <p>
                <input type="radio" id="reg_field_2" name="reg[fields][2]" value="1">
                <label for="reg_field_2">"It has something to do with computer"</label>
            </p>

            <p>
                <input type="radio" id="reg_field_3" name="reg[fields][2]" value="2">
                <label for="reg_field_3">"I know how to print 'hello world'"</label>
            </p>
            <p>
                <input type="radio" id="reg_field_5" name="reg[fields][2]" value="4">
                <label for="reg_field_5">"I am a professional with > 10 years experience"</label>
            </p>
        </div>

        <div class="button">
            <?php
            $button_html = get_submit_button('Register', 'primary', 'submit_button_name', false);
            echo $button_html;
            ?>
        </div>
    </div>
</form>

The form and POST is set by a shortcode:

function eventregistration_shortcode($atts)
{
    if (is_single() || is_page()) {
        $default = array(
            'frmid' => 'a'
        );
        $a = shortcode_atts($default, $atts);

        ob_start();

        new Shortcodes_EventRegistration($a['frmid']);

        $output_string = ob_get_contents();
        ob_end_clean();
        return $output_string;
    } else {
        return "not single";
    }
}
add_shortcode('events_registration', 'eventregistration_shortcode');

Summary:

• When a visitor registers for an event on the LIVE website, the information is stored TWICE in the database and e-mails (when activated) are send twice too.
• Placing “echo’s” in the function that stores the information are only shown ONCE
• The short code is placed once in the page (happened once, not making that mistake again)
• This works perfectly fine on LOCAL website (wamp server)

What am I doing wrong?